Engineering cell attachments to scaffolds in cartilage tissue engineering

One of the challenges of tissue engineering, a promising cell-based treatment for damaged or diseased cartilage, is designing the scaffold that provides structure while the tissue regenerates. In addition to the scaffold material’s biocompatibility, mechanical properties, and ease of manufacturing, scaffold interactions with the cells must also be considered. In cartilage tissue engineering, a range of scaffolds with various degrees of cell attachment have been proposed, but the attachment density and type have yet to be optimized. Several techniques have been developed to modulate cell adhesion to the scaffold. These studies suggest that the need for cell attachment in cartilage tissue engineering may vary with cell type, stage of differentiation, culture condition, and scaffold material. Further studies will elucidate the role of cell attachment in cartilage regeneration and enhance efforts to engineer cell-based cartilage therapies.     

多孔钛骨组织工程支架设计及孔结构表征

针对目前骨组织工程支架微孔结构难以准确设计制备的问题,提出了一种基于点云的参数化建模+3D打印新方法。通过提取cube(C)、diamond(D)、gyroid(G)3种结构的型面函数点云数据,完成对不同孔结构特征的参数化建模。通过对模型有限元力学分析,对不同孔结构特征的多孔钛骨组织支架进行力学设计与订制。借助激光选区熔融(SLM)3D打印技术,完成对不同孔特征的骨组织支架快速成型。对多孔钛骨组织支架进行了相关材料学表征,包括孔结构表征与力学性能测试。结果表明:参数化模型的快速成型制造,能够有效地设计制备钛合金骨组织工程支架的孔结构特性,且可有效设计订制支架的力学性能,从仿生的角度实现多孔钛合金骨组织工程支架生物学功能的设计优化。     

不同类型多孔结构生物材料支架制备及其性能优化

多孔支架是组织工程应用中的关键环节,类似细胞外基质的作用,支撑细胞的粘附和随后细胞向组织的衍化。虽然目前已采用多种制备技术研发出大量的多孔支架,但是多孔生物材料支架的制备和性能优化,仍然是组织工程支架领域的研究热点。结合实验室工作,综述了多种制备不同类型多孔结构生物材料支架的制备技术,主要包括颗粒和纤维堆积型支架、泡沫浸渍法支架和颗粒制孔支架等的制备技术,并阐述了这些制备技术对多孔结构支架的孔结构、贯通性和力学性能的改善效果。其目的旨在提供满足组织工程需求的多孔生物材料支架。     

The development of biocomposite nanofibers for tissue scaffolding applications

The last decade has seen significant progress in the production of nanofibers by electrospinning. One of the major drivers to this progress is the potential use of nanofibrous structures as scaffolds for engineering tissues in regenerative medicine. Electrospun fibers are capable of emulating the nanofibrous architecture of the native extracellular matrix. They can potentially provide in-vivo-like nanomechanical and physicochemical signaling cues to the cells to establish apposite cell-scaffold interactions and promote functional changes between and within cells toward synthesis of a genuine extracellular matrix over time. In this context, this paper presents a brief overview of a scaffold design strategy. It also presents recent research pertaining to developing biomimetic and bioactive nanofibrous tissue scaffolds through electrospinning biocomposite nanofibers of organic-organic and inorganic-organic hybrids, which are potentially applicable to soft and hard tissue engineering.     

A plasma-assisted bioextrusion system for tissue engineering

A challenge for tissue engineering is to produce synthetic scaffolds of adequate chemical, physical and biological cues effectively. This paper describes a plasma-assisted bio-extrusion system to produce functional-gradient scaffolds; it comprises pressure-assisted and screw-assisted extruders, and plasma jets. This paper also describes how the system conducts plasma surface modification during the polycaprolactone scaffold fabrication process. Water contact angle and in vitro biological tests confirm that the plasma modification alters the hydrophilicity properties of synthetic polymers and promotes proliferation of cells, leading to homogeneous cell colonization. The results suggest this system is promising for producing functional gradient scaffolds of biomaterials.     

新型多孔镁压缩性能的有限元分析

利用有限元方法建立了激光打孔制备的直孔型多孔镁样品的压缩模型,系统分析了孔隙率、孔径及孔的排布对多孔镁样品压缩性能的影响,初步探讨了多孔镁在压缩过程中的变形规律.模拟计算结果表明,随着孔隙率、孔径的增加和孔的排布角的减小,多孔镁压缩曲线下移,屈服强度和弹性模量随之下降;多孔镁的压缩变形规律符合金属的最小阻力定律.     

Fabrication of Bioceramic Bone Scaffolds for Tissue Engineering

In this study, microhydroxyapatite and nanosilica sol were used as the raw materials for fabrication of bioceramic bone scaffold using selective laser sintering technology in a self-developed 3D Printing apparatus. When the fluidity of ceramic slurry is matched with suitable laser processing parameters, a controlled pore size of porous bone scaffold can be fabricated under a lower laser energy. Results shown that the fabricated scaffolds have a bending strength of 14.1 MPa, a compressive strength of 24 MPa, a surface roughness of 725 nm, a pore size of 750 μm, an apparent porosity of 32%, and a optical density of 1.8. Results indicate that the mechanical strength of the scaffold can be improved after heat treatment at 1200 °C for 2 h, while simultaneously increasing surface roughness conducive to osteoprogenitor cell adhesion. MTT method and SEM observations confirmed that bone scaffolds fabricated under the optimal manufacturing process possess suitable biocompatibility and mechanical properties, allowing smooth adhesion and proliferation of osteoblast-like cells. Therefore, they have great potential for development in the field of tissue engineering.     

石墨烯基涂层的性质及在抗菌和组织工程中的应用

石墨烯材料--石墨烯纳米片(Graphene nanoflakes,GFs)、氧化石墨烯(GO)或还原氧化石墨烯(rGO)、化学气相沉积技术制备的石墨烯膜(CVD-G),自问世起,迅速成为社会各界广泛关注的新型碳纳米材料。通过转移方法或者溶剂助技术,可以将CVD-G和表面含有亲水基团的GFs或GO涂覆于基体表面,形成石墨烯基涂层,涂层以其独特的形貌、结构、物理化学性质,呈现出良好的抗菌活性和细胞外基质特点,显著影响细胞的粘附、增殖和分化等行为。经过近十年的研究,生物活性石墨烯基涂层材料在细胞培养、细胞生长、组织工程支架和生物医疗器械中展示出巨大的应用潜力。着重围绕石墨烯涂层的成分和制备方法,总结具有抗菌活性的石墨烯材料所取得的重要成果与最新进展,围绕石墨烯基二维涂层(涂覆于基底的二维表面)和石墨烯基三维结构(基底为三维支架)对多种哺乳细胞的相容性和细胞行为调控,综述了石墨烯材料在组织工程支架和植入体表面改性中的研究进展,提出了生物活性石墨烯基涂层的研制方向与应用展望等。     

Effect of pore geometry and loading direction on deformation mechanism of rapid prototyped scaffolds

Rapid prototyping is a promising technique for producing tissue engineering scaffolds due to its capacity to generate predetermined forms and structures featuring distinct pore architectures. The objective of this study is to investigate the influences of different pore geometries and their orientation with respect to the compressive loading direction on mechanical responses of scaffolds. Plastic models of scaffolds with cubic and hexagonal unit cells were fabricated by three-dimensional (3-D) printing. An in situ imaging technique was utilized to study the progressive compressive deformation of the scaffold models. In both cubic and hexagonal geometries, organized buckling patterns relevant to each unit cell were observed at the onset of plastic deformation. These patterns were in good agreement with the elastic stress concentration patterns generated by finite element simulation. Uniaxial compression tests conducted on both geometries revealed that the stress–strain pattern may vary significantly by changing the loading direction. A secondary stress softening phenomenon was observed where limited pore deformation caused 3-D structure bending. However, when loading direction was adjusted such that deformation was localized on all pores simultaneously, a monotonically increasing stress was observed. These results accentuate the critical role of pore geometry and orientation with respect to the principal loading axis in designing functional tissue engineering scaffolds.     

基于SLM的Ti-6Al-4V人工骨支架的结构设计

设计了6种Ti-6Al-4V人工骨支架,利用SLM(选择性激光熔化)进行制备。采用万能材料实验机结合高速摄像机分析支架的压缩过程,并利用Ansys进行分析。结果表明：支架的立柱直径对支架的力学性能参数影响较大,横梁直径对其影响较小;在相同高度下,支架横梁直径增大、层数增多或立柱直径增大,均使结构长径比减小,使结构稳固且支架承载能力提高;支架的力学性能应与周围骨组织相匹配,经过分析,3种结构的支架力学性能参数与人体股骨相近,故可作为股骨的人工骨支架。     

组织工程化三维仿骨支架重建股骨头坏死区研究

首先研制出具有取向性类骨结构的β-TCP三维仿骨支架,经过仿生类骨处理和组织工程化后,植入犬的股骨头坏死区,30周后取出股骨头进行分析研究.与此同时开展了几种支架材料重建股骨头坏死区的力学性能分析和模拟.结果显示,具有取向性类骨结构的β-TCP三维仿骨支架具有很好的生物相容性和力学相容性.动物实验研究表明:组织工程化三维仿骨支架诱导生长出新的骨小梁,并伴有β-TCP降解,这为修复或重建股骨头局部坏死区提供了一种有希望的新途径.     

钛合金变形Gyroid单元梯度多孔结构设计与分析

研究一种具有径向和轴向孔径梯度的变形Gyroid单元多孔结构参数化设计方法,采用激光选区熔化成形(selective laser melting, SLM)技术,制备出孔隙率为60%和75%的钛合金变形Gyroid单元梯度多孔结构样件。使用有限元法(finiteelementmethod,FEM)对4组梯度多孔支架模型及2组均质模型进行静力学仿真分析,对制备的钛合金梯度多孔样件进行力学性能测试,并与已测试过的均质样件进行力学性能对比分析。有限元计算结果与力学性能试验结果共同表明：变形Gyroid单元多孔结构力学性能随孔隙率的升高而降低,孔隙率相同时,径向梯度多孔支架力学性能优于均质多孔支架,更适用于皮质骨的骨缺损修复,轴向梯度多孔支架力学性能相比均质多孔支架有所减弱,更适用于松质骨。     

多孔Fe-Mn合金表面微纳形貌调控及其生物相容性评价

铁基可降解金属因其良好的生物相容性和优异的机械性能,在骨科植入物领域具有广阔的应用前景,但必须突破其降解速率过慢的瓶颈问题。本研究通过电化学技术对3D打印多孔铁锰合金(Fe-30Mn)支架表面进行去合金化处理。通过扫描电镜观察发现,以盐酸和氯化钠分别作为去合金化处理介质溶液,可以在支架表面形成多微孔网络结构和片状纳米结构。接触角和粗糙度测试显示,2种微纳结构的构建均显著改善了Fe-30Mn支架表面亲水性,并提升了其表面粗糙度,多微孔网络结构更加粗糙并且亲水性更好。利用静态浸泡法和电化学耐腐蚀实验评估合金化处理前后支架的腐蚀速率,发现表面微纳结构的形成可加速Fe-30Mn支架的降解。建立体外成骨细胞培养模型,通过激光共聚焦观察及细胞增殖测试发现,经合金化处理的2种支架均能支撑细胞的贴附和增殖,具有良好的细胞相容性。结果表明,经电化学去合金化处理后,Fe-30Mn支架的降解速度得以增强,同时保持了良好的生物相容性,有望在骨修复领域得到较好应用。     

Three-dimensional chitosan-nanohydroxyapatite composite scaffolds for bone tissue engineering

We describe the structure of biodegradable chitosan-nanohydroxyapatite (nHA) composites scaffolds and their interaction with pre-osteoblasts for bone tissue engineering. The scaffolds were fabricated via freezing and lyophilization. The nanocomposite scaffolds were characterized by a highly porous structure and pore size of ∼50–125 μm, irrespective of nHA content. The observed significant enhancement in the biological response of pre-osteoblast on nanocomposite scaffolds expressed in terms of cell attachment, proliferation, and widespread morphology in relation to pure chitosan points toward their potential use as scaffold material for bone regeneration.     

Novel design approach for the creation of 3D geometrical model of personalized bone scaffold

Bone scaffolds provide a structural support for tissue development. Existing bone scaffolds are mainly characterized by complex porous designs whose shortcomings are a low level of permeability for growing tissue, and a difficult design customization. Scaffolds with nucleuses (rods or lattices) as basic elements should improve bone regeneration and enable higher design flexibility. In this paper, we present two new methods for building 3D geometrical models of personalized scaffolds, which are based on method of anatomical features. Methods are demonstrated in the case of scaffold for the mandible bone. This approach greatly reduces the designer effort and time, while enabling easy personalization of scaffolds’ shape and geometry.     

RP技术新进展:细胞打印的初步研究

快速成形技术采用离散／堆积的原理，直接成形复杂精细的结构器件，在组织工程研究中，快速成形技术多应用于组织工程支架的制备。而将活细胞或细胞／基质作为堆积的对象进行堆积成形，是一种符合自然生长规律的新型快速成形技术，为器官的直接三维成形提供了方法。本研究对细胞在凝胶中的生长及打印工艺进行了初步的探索。     

Surface modification of PLGA/β-TCP scaffold for bone tissue engineering: Hybridization with collagen and apatite

The objective of this experiment is to produce a novel scaffold composed of poly (lactic-co-glycolic acid) (PLGA)/β-tricalciumphosphate (β-TCP) skeleton covered with apatite/collagen sponge. BMSCs were used to evaluate the cell behavior on the hybrid scaffold. Cell morphology on the surfaces of PLGA/β-TCP skeleton and PLGA/β-TCP skeleton with apatite/collagen sponge composite coating was studied by scanning electron microscopy (SEM). Cell proliferation was assessed by cell number counting. Differentiated BMSCs function was monitored by measuring alkaline phosphates activity of the cells. These results demonstrated that the apatite/collagen sponge composite coating could improve cell proliferation and ALP activity of the hybrid scaffolds and increase its hydrophilicity after hybridization. The experiment suggested that the PLGA/β-TCP skeleton with apatite/collagen sponge composite coating is promising as a candidate 3D substrate for bone tissue engineering.     

Novel fabrication of forsterite scaffold with improved mechanical properties

In this study, the macroporous forsterite scaffolds with highly interconnected spherical pores, with sizes ranged from 50 to 200 μm have been successfully fabricated via gelcasting method. The crystallite size of the forsterite scaffolds was measured in the range 26-35 nm. Total porosity of different bodies sintered at different sintering temperatures was calculated in the range 81-86%, while open porosity ranges from 69 to 78%. The maximum values of compressive strength and elastic modulus of the prepared scaffolds were found to be about 2.43 MPa and 182 MPa, respectively, which are close to the lower limit of the compressive strength and elastic modulus of cancellous bone and the compressive strength is equal to the standard for a porous bioceramic bone implant (2.4 MPa). Transmission electron microscopy analyses showed that the particle sizes are smaller than 100 nm. In vitro test in the simulated body fluid proved the good bioactivity of the prepared scaffold. It seems that, the mentioned properties could make the forsterite scaffold appropriate for tissue engineering applications, but cell culture and in vivo tests are needed for more confidence.     

Bioactive Ca-P scaffolds used for bone reconstruction

1　INTRODUCTIONSkeletalreconstructionorregenerationisre quiredincasesinvolvinglargedefectscreatedbytu morresection ,trauma ,andskeletalabnormalities .Graftsandflapsofautogenoustissuearetwoofthemostsuccessfulmeansofreconstructionbecausetheyallowthetransplantationofbonecontainingbioactivemolecules,livecells ,andfrequently ,avascularsup plythatallowthetransplanttosurviveandremodeleveninhostileradiatedenvironments .However ,onlyaminimalamountoftissuecanbeharvestedforauto grafts,anditisverydiff…     

仿生纳米纤维支架促进骨组织再生

人口老龄化,疾病以及交通事故等造成大量的人体骨组织损伤和丢失。如何实现骨组织缺损的快速修复与再生成为临床医学研究的重要课题和目标,而生物医用材料在其中发挥着极其重要的作用。目前临床上常用的骨组织修复材料如自体骨、异体骨、合成材料（金属,陶瓷,高分子）等都存在各种各样的问题,无法实现大规模的应用和骨组织的快速有效再生。而骨组织工程学科研究多孔支架结合细胞和生长因子来实现骨组织再生,以鳃决骨科临床面临的问题为目的。最近十多年来,三维纳米纤维支架由于可以仿天然细胞外基质的结构和形态而显示出较强的促进细胞增殖、成骨分化以及骨组织修复再生的能力。主要综述具有仿生的纳米纤维及其复合支架材料的制备技术以及他们在增强细胞功能、干细胞成骨分化、及其骨组织再生中的应用。